China is set to launch the country’s next satellite as part of its robotic lunar-exploration program.

The satellite, called Queqiao, is essential infrastructure for China’s lunar plans. It will be stationed about 40,000 miles behind the moon and provide a communications link for a rover that is designed to land and explore the lunar far side, which never faces Earth.

The satellite is needed because it’s impossible to directly communicate with the Moon’s far side. The Queqiao satellite will relay signals between the rover and our planet.

Later this year China will send the second part of the mission: a lunar lander to deploy a rover on the far side to explore the moon’s Aitken basin. The basin is the largest crater in the solar system and could hold clues about the way the moon formed.

A successful landing will be a first, no country has yet landed on the far side of the moon.

The rocket launching Sunday will also carry a Dutch radio antenna designed to catch faint celestial signals from the early days of the universe.